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 * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

package javax.lang.model.util;

import java.util.List;
import java.util.Map;

import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.AnnotationValue;
import javax.lang.model.element.Element;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.Name;
import javax.lang.model.element.PackageElement;
import javax.lang.model.element.TypeElement;
import javax.lang.model.element.VariableElement;

/**
 * Utility methods for operating on program elements.
 * 
 * <p>
 * <b>Compatibility Note:</b> Methods may be added to this interface in future
 * releases of the platform.
 * 
 * @author Joseph D. Darcy
 * @author Scott Seligman
 * @author Peter von der Ah&eacute;
 * @see javax.annotation.processing.ProcessingEnvironment#getElementUtils
 * @since 1.6
 */
public interface Elements {

	/**
	 * Returns a package given its fully qualified name.
	 * 
	 * @param name
	 *            fully qualified package name, or "" for an unnamed package
	 * @return the named package, or {@code null} if it cannot be found
	 */
	PackageElement getPackageElement(CharSequence name);

	/**
	 * Returns a type element given its canonical name.
	 * 
	 * @param name
	 *            the canonical name
	 * @return the named type element, or {@code null} if it cannot be found
	 */
	TypeElement getTypeElement(CharSequence name);

	/**
	 * Returns the values of an annotation's elements, including defaults.
	 * 
	 * @see AnnotationMirror#getElementValues()
	 * @param a
	 *            annotation to examine
	 * @return the values of the annotation's elements, including defaults
	 */
	Map<? extends ExecutableElement, ? extends AnnotationValue> getElementValuesWithDefaults(
			AnnotationMirror a);

	/**
	 * Returns the text of the documentation (&quot;Javadoc&quot;) comment of an
	 * element.
	 * 
	 * @param e
	 *            the element being examined
	 * @return the documentation comment of the element, or {@code null} if
	 *         there is none
	 */
	String getDocComment(Element e);

	/**
	 * Returns {@code true} if the element is deprecated, {@code false}
	 * otherwise.
	 * 
	 * @param e
	 *            the element being examined
	 * @return {@code true} if the element is deprecated, {@code false}
	 *         otherwise
	 */
	boolean isDeprecated(Element e);

	/**
	 * Returns the <i>binary name</i> of a type element.
	 * 
	 * @param type
	 *            the type element being examined
	 * @return the binary name
	 * 
	 * @see TypeElement#getQualifiedName
	 * @jls3 13.1 The Form of a Binary
	 */
	Name getBinaryName(TypeElement type);

	/**
	 * Returns the package of an element. The package of a package is itself.
	 * 
	 * @param type
	 *            the element being examined
	 * @return the package of an element
	 */
	PackageElement getPackageOf(Element type);

	/**
	 * Returns all members of a type element, whether inherited or declared
	 * directly. For a class the result also includes its constructors, but not
	 * local or anonymous classes.
	 * 
	 * <p>
	 * Note that elements of certain kinds can be isolated using methods in
	 * {@link ElementFilter}.
	 * 
	 * @param type
	 *            the type being examined
	 * @return all members of the type
	 * @see Element#getEnclosedElements
	 */
	List<? extends Element> getAllMembers(TypeElement type);

	/**
	 * Returns all annotations of an element, whether inherited or directly
	 * present.
	 * 
	 * @param e
	 *            the element being examined
	 * @return all annotations of the element
	 * @see Element#getAnnotationMirrors
	 */
	List<? extends AnnotationMirror> getAllAnnotationMirrors(Element e);

	/**
	 * Tests whether one type, method, or field hides another.
	 * 
	 * @param hider
	 *            the first element
	 * @param hidden
	 *            the second element
	 * @return {@code true} if and only if the first element hides the second
	 */
	boolean hides(Element hider, Element hidden);

	/**
	 * Tests whether one method, as a member of a given type, overrides another
	 * method. When a non-abstract method overrides an abstract one, the former
	 * is also said to <i>implement</i> the latter.
	 * 
	 * <p>
	 * In the simplest and most typical usage, the value of the {@code type}
	 * parameter will simply be the class or interface directly enclosing
	 * {@code overrider} (the possibly-overriding method). For example, suppose
	 * {@code m1} represents the method {@code String.hashCode} and {@code m2}
	 * represents {@code Object.hashCode}. We can then ask whether {@code m1}
	 * overrides {@code m2} within the class {@code String} (it does):
	 * 
	 * <blockquote> {@code assert elements.overrides(m1, m2,
	 *          elements.getTypeElement("java.lang.String")); } </blockquote>
	 * 
	 * A more interesting case can be illustrated by the following example in
	 * which a method in type {@code A} does not override a like-named method in
	 * type {@code B}:
	 * 
	 * <blockquote> {@code class A public void m() {} } }<br>
	 * {@code interface B void m(); } }<br>
	 * ...<br>
	 * {@code m1 = ...;  // A.m }<br>
	 * {@code m2 = ...;  // B.m }<br>
	 * {@code assert ! elements.overrides(m1, m2,
	 *          elements.getTypeElement("A")); } </blockquote>
	 * 
	 * When viewed as a member of a third type {@code C}, however, the method in
	 * {@code A} does override the one in {@code B}:
	 * 
	 * <blockquote> {@code class C extends A implements B <br>
	 * ...<br>
	 * {@code assert elements.overrides(m1, m2,
	 *          elements.getTypeElement("C")); } </blockquote>
	 * 
	 * @param overrider
	 *            the first method, possible overrider
	 * @param overridden
	 *            the second method, possibly being overridden
	 * @param type
	 *            the type of which the first method is a member
	 * @return {@code true} if and only if the first method overrides the second
	 * @jls3 8.4.8 Inheritance, Overriding, and Hiding
	 * @jls3 9.4.1 Inheritance and Overriding
	 */
	boolean overrides(ExecutableElement overrider,
			ExecutableElement overridden, TypeElement type);

	/**
	 * Returns the text of a <i>constant expression</i> representing a primitive
	 * value or a string. The text returned is in a form suitable for
	 * representing the value in source code.
	 * 
	 * @param value
	 *            a primitive value or string
	 * @return the text of a constant expression
	 * @throws IllegalArgumentException
	 *             if the argument is not a primitive value or string
	 * 
	 * @see VariableElement#getConstantValue()
	 */
	String getConstantExpression(Object value);

	/**
	 * Prints a representation of the elements to the given writer in the
	 * specified order. The main purpose of this method is for diagnostics. The
	 * exact format of the output is <em>not</em> specified and is subject to
	 * change.
	 * 
	 * @param w
	 *            the writer to print the output to
	 * @param elements
	 *            the elements to print
	 */
	void printElements(java.io.Writer w, Element... elements);

	/**
	 * Return a name with the same sequence of characters as the argument.
	 * 
	 * @param cs
	 *            the character sequence to return as a name
	 */
	Name getName(CharSequence cs);
}
